Have them show up with their own material. Stuff that they know well, as opposed to the latest CD they just picked up, but what the hell, let them bring as much as they want. Be prepared to dig in your own collection for similar music. Watch for cues that you are switching tracks too quickly, or lingering too long. Pay attention to their reactions to your music, be prepared for them not to be interested in your favorites, and adapt appropriately.
That's mostly what others have been saying. The part I want to add is that some people just don't care. If you're getting people in front of your stereo with the invitation "Hey, come listen to my stereo!" then they probably know what they're in for and are somewhat amenable (as opposed to ambushing random visitors, which I've never had much success with). But even so, there are a lot of people who are only interested in the status symbol of "how much bass?" or "how much volume?" or "how much chrome?" It doesn't occur to some people that they should stop making chit-chat when you press play. Not that these people are cretins, but not everyone cares about this particular hobby.
If you can reach these people great, but you might not see any reaction from a single listening session. I had a friend / room mate who listened to my stereo for years and never cared a whit for high fidelity. Later, he had his own place, got his own (trashy) stereo, and only after going back and forth between his own stereo and mine for a significant amount of time did he start to express that he wished for better sound at his house. Active hi-fi preaching until this time was met with vacant smiles.
So show off your setup, and if your guest isn't interested show off some music, and if he still isn't interested be prepared to talk about something else.
If you're looking for song reccomendations, there's a music area under "everything else" on this forum. Try this:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=62876
PS - congrats on the OB build! I look forward to finding a pair to audition tho I haven't the room for enormous baffles, myself.